Determine the interaction of a new organophosphorus insecticide (AC 92,100 or Counter) with 3 Iowa soils and the southern corn rootworm. Study the insecticide residues present in carabid ground beetles and the soil they inhabit to determine what influences these chemicals might have in regulating beetle populations. Standard extraction procedures and gas-liquid chromatographic methods as used by the Environmental Protection Agency and Food and Drug Administration will be followed.